Manufacture of light sensitive materials



Jan- 5, 1,937. I w. DIETERLE z-r AL '2,066,966

MANUFACTURE OF LIGHT SENSITIVE MATERIALS Filed Feb. 4, 1932 7504150 also 60a .ua .foo

Inventar@ l sion the sensitivity of which is raised over the duced in their molecule an amino group and cor-i responding to the general formula Formula 1:

, y I Y =S, Se, Te, Y'=S, Se,.Te, C(CH3) i, O,

/R i W=H, N alkyl, alkoxy, 3o

. R' p A, A', r, r and R'=II', alkyl, B =H, alkyl, alkoxy, R =H, alkyl, aryLacyl,v

n =0 or l, X =halide, C104, are particularly suited for sensltlzingphoto` graphic emulsions. The dyes are characterized by their sensitizing eiliciency and their stabilityv against agents used for stabilizing the emulsions,

' Patented Jari. 5,151.93?V

y MATERIALS Walter Dieterle and Walter Zeh, Dessauv in Anhalt, and Werner Zerweck, Frankfort-on-the- Main-Fechenheim, Germany, assignors to Agfa. Ansco Corporation, Binghamton, N. Y., a cori poration of New York Application February 4,1932, Serial No. 590,940

In Germany February 7, 1931 .v v 9 claims. Our present invention relates to the sensitizing of photographic emuleA 1ns.',

One of its objects is to provide such an'emulrange of wave lengths to which the emulsion is normally sensitive. Further objects will be seen from the detailed specification following hereafter.

We have found that the cyanines having introfor instance, potassium bromide. y

The amino groupv having the radicals R and R' may be introduced at the position 4, 5, 6 or 1,

We will now discuss the diierent groups of our WWriv:lssif':dyeswin theliglit of the formulae,

vwhich result. from the general formula given above by replacing Z indicated.

The groups are corresponding to the formula:

Formula 2: l

and may be divided into symmetrical compounds and unsymmetrical compounds. symmetrical by the different radicals compounds are only the benzthiazole-methine cyanines and benzthiazoleJtrimethinecyanines, provided that Y is sulfur, which may loe derived from Formula 2 if W represents and is introduced in both benzthiazole nuclei at corresponding positions. 'Ihe benzthiazole-methinecyanines differ from the benzthiazole-trimethinecyanines in that the index n of the part putvin'parenthesis is 0 or 1 respectively. They correspond to the following formulae:

Formula. 5 (benzthiazole-methinecyanines) Formula'l 6 (benzthiazole-trimethinecyanines) In the formula of the benzthiazole-methinecyanines the amino group may take the places 4, v5, 6 and 1. R may represent H, or alkyl, for instance,

.. methyl,-ethyl, oraryl, for" instance, phenyl,

naphthyl,or a substituted aryl, or acyl, for instance, benzoyl, acetyl and propionyl. R' may loev alkyl in the case of R being alkyl or aryl, or R' is hydrogen in the oase of R being acyl. X may represent any suitable anion that will precipitate the dye, for instance, a halide, paratoluene sulfonate, alkylosulfate, perchlorate, nitrate, or the like. A of Formula 2 may be H or alkyl, like l methyl or ethyl'- for the' benzthiazole-methin'- cyanines. Due to the symmetrical structure of the compounds r and 1 of Formula 2 are represented by the same radicals r, for instance, H, or an alkyl radical, such as methyl or. ethyl.

The benzthiazole-trimethinecyanines (cf. Formula 6) may be substituted in the manner indicated for the benzthiazole-methinecyanines, however, in the molecule of these compounds the carbon bridge likewise may be substituted. Due to 4 the symmetrical structure of the benzthiazoletrimethinecyanines A and A of Formula 2 reprefor instance, beingv H or if being the same group this group has a position different from that of the Rf group in the other nucleus. This statement is v illustrated by the following formulae:

Formula 7:

In Formulae 7 and 8, likewise in all unsymmetrical compounds which can be derived from general Formula 1, in the bridge the substituents A or A' may represent an alkyl, for instance, methyl or ethyl, it being understood that A is different from A', for example if A is a methyl A may be ethyl. B is for the asymmetric compounds always hydrogen. 'I'he amino group may have inboth Formulae '7 and 8 the positions l, 5, 6 and 1. R and R may represent the same radicals as indicated for the benzthiazole-methinecyanines, X likewise represents the same groups as in the benzthiazolemethinecyanines. T and r' may be in Formulae 7 and 8, as Well as in all unsymmetrical cyanines derived from general Formula 1 the same radicals or they may be different and represent the same radicals enumerated for the benzthiazole-methinecyanines. In order to illustrate the nomenclature Ait may be in Formula'l;

If in this case the amino group be in position 6 we obtain the compound [S-ethyl-S-diethylaminobenzthiazole- (2) l l-[S-methyl-benzthiazole- (2) -a-methyl-y-ethyl-trimethinecyanine iodide of the lformula:

The amino groups may have the positions 4, 5,

and 1. Y and Y' are different elements of the group comprising S, Se, Te, C(CHa)2 and O. If Y is sulfur, Yf selenium and n is O we call the dye a v-"benzthiazole-benzselenazole-methinecyanine. In the case of Y being sulfur, Y being C(CH3)2,

and n being O W`e call the dye a benzthiazoleindole-methinecyanine, and if under the same conditions Y' is O we call the dye a benzthiazolebenzoxazole-methinecyanine.

In Formula 4 substitution may be effected in the same manner as indicated for Formula 3 with respect to R, R', A, A', X, r and r'. The quinoline nucleus maybe substituted in known manner by alkyl groups, alkoxy groups and amino or substituted amino groups. Furthermore this nucleusmay be linked to the carbon bridge in position 2 or 4. In case of the quinoline nucleus being linked to the bridge in position 2 and Y is [quinoline-y) l--methinecyanine and a [benzthiazole- (2) l-[quinoline- (4) methinecyanine if the quinoline nucleus is linked in position 4 to alkyl groups such as methyl or ethyl groups, or

vchromatic sensitization which likewise remains alkoxyl groups, such as methoxy groups or ethoxy groups, or both alkyl and alkoxyl groups.

With vrespect to the sensltizing action of our new compounds reference is made to the accom-- panying drawing in which Figures 1, 2 and 3 show spectrograms of different dyes added to photographic emulsions for Vircreasing their sensitiveness to rays of different wave length.

In these spectograms vthe vabscissae are graduated in millimicrons (mi) while the ordinates are graduated in divisions denoting the blackening of the tested i'llm. The blackenirigs are obtained by exposing the nlm in a diffraction grating spectograph of Carl Zeiss Jena provided with a Rowland diffraction grating and illuminating with a nitra -lamp of 100 watt through a stage slot. The emulsion showing curve i contains the known dye Pinacyanol in -a quantity of about 20 milligrams on 1kg. of an emulsion ready for being cast corresponding to about 140 grams of dry emulsion. The em'ulsion showing curve 2 is sen- 3 sitized with about 10 milligrams of bis-'.[B-ethyl- 5 diethylaminobenzthiazole (2) l-trimethine cyanine iodide.(see Example 8) incorporated in 1 kg. of an emulsion ready for being cast corrsponding to about 140 grams of dry emulsion. The emulsion showing curve' 3 is sensitized with a mixture of about 16 milligrams of the known dye [3-ethyl-benzselenazole- (2) l- ['1-ethy1- quin--y oline-(2)] methinecyanine iodide and about 12 milligrams .of bis-[3-ethyl-5-diethylamino-benzthiazole- (2) l-trimethinecyan'ine iodide, incorporated in 1 kg. of an emulsion ready for being cast corresponding to about 140 grams of dry emulsion; The emulsion used lwas obtained according to the boiling process, but an emulsion 'made according .to the ammonia process will give analogous results. When comparing thecurves the superiority of our new dyes will be easily seen. This superiority is still more evident when considering that on an addition of 2 milligrams of potassium bromide to hitherto known dyes the intensityis essentially decreased by addition of such quantities of potassium bromide to the dry emulsion. The spectrogram, Figure 3, of the emulsion containing the mixture of [3-ethyl-benzselenazole-(2) ]'v[1 ethyl-quinoline- (2) l-methinecyanine iodide and bis-[3-ethyi-54diethylamino-benzthiazole (2) ltrimethinecyanine iodide shows a very good panunaltered when adding potassium bromide to the said emulsion.

Other dyes of those herein described yield similar curves when incorporated in a photo- .graphic emulsion and investigating'this emulsion under the conditionsvset forth.

-By introducing different substituents' in the molecule of the dyes a displacement of the range of -sensitivity towards the region of the longer trimethinecyanine iodide produces a maximum sensitiveness to a wave length of about 595 Mi.

(2) Contrary thereto'our new dye bis-[3-ethyl 6 diethylamino-benzthiazole (2)] trimethinecyanine iodide produces .a maximal sensitiveness to a wave length of about 655 pp.. The introduction of one diethylamino group into the benzene nucleus of the benzthiazoletrimethinecyanine at the place of hydrogen effects a displacementof about mi, the relations being additive.

(3) `The known dye bisl 3ethylbenzselenazole (2)]-trimethinecyanine iodide effects a maximum sensitiveness to a wave length of about 615 p41..

` (4) However, when using our, new dye bis-[3- methinecyanine-'iodide a maximum sensitiveness to a wave length of 670 a is reached.

Thus the introduction of one diethylamino group into the benzene nucleus of the benzselenazole-trimethinecyanines at the place of hydrogen effects a displacement of about 28 mi.

As seen there is a slight difference between the replacement ofhydrogen in thel benzene nucleus by a substituted amino group in the molecule of the thiazole-methinecyanines and the selenazolemethinecyanines. It is to be understood that the foregoing statement is given only by'way of example.. Other radicals which have already been mentioned may represent R and R'; furthermore A, A' and B may likewise represent different radicals already mentioned which cause a displacement of/the range of sensitiveness with respect to each other. The replacement of r and r' by different Aradicals is of minor efciency for displacing the range of sensitiveness'.I The radicals representing X are of no influence in the purpose set forth. The influence `on the displacement of the maximum sensitiveness and on the intensity of the sensitiveness can easily be determined by a few comparative experiments.

The dyes are obtainable according to the desired solubility .in form of the bromide, iodide, perchlorate etc. and are used in a quantity: as usual for the known sensitizing dyes. This quantity amountsto 8 to 25 milligrams per 1 kg. of emulsion ready for Vbeing cast which contains about 9 per cent of gelatin, 4.5 per cent of silverhalide, the rest being water. We do not wish to limit our invention exactly to the quantities justindicated, the most suitable amount will be found in each particular case by a few simple experiments. Thedyes may be added to the emulsion in form of solutions. Suitable solvents are the alcohols, forinstance, methyl or ethyl alcohol, which may be used anhydrous or diluted with water. The dyes are applied to the emulsion during any stage of their production, however they are preferably ladded to the finished emulsion before being cast. The dyes maylikewise be added by coating the emulsion'with them orv by bathing the finished photographic materials `in a bathin which the dye is dissolved.

starting material for preparing the dyes lis-'de-v scribed in Examples 1 to 9. Otherbases than those described in these examples may be proogous to knownmethods and illustrated in EX- amples 10 to 26.

amino-benzthiazole corresponding to the formula H 7 s IN o l 2 5 4 \I1`l/ CH:

is described in U. S. Patent 1,758,385 and reference is made thereto.

Example 2.-The base 2-methyl-5-aminobenzthiazole corresponding to the formula HN 4 Mall-CH:

is obtained by reducing the corresponding nitro compound whose method of preparation is`known (cf. Friess, Ann. 4.54 page 177), for instance, with iron and acetic acid. The amino 'compound iseasily soluble in alcohol, glacial acetic acid and benzene. It` can be easily recrystallized from water or benzene' and forms colorless crystals which melt at about 103 C.

Example 3.-The base 2.6-dimethyl-5-aminobenzthiazole corresponding to the formula a/ on,

can be obtained in two ways.

According to the first way we proceed as follows: 2-amino-4-acetylamino-toluol corresponding to the formula 5 HzN 4 \CO CH:

isV first rhodanated with NH4SCN and Br in its methyl-alcoholic solution in the manner described in U. S. Patent 1,787,315 and then with an aqueous ammoniacal solution. The formed product,

benzthiazole corresponding to the formula Hic s H/N 3/ NH,

obtained from its aqueous solution in the form of colorless crystals which melt at about 200 C. is split up by heating the same with an aqueous solution of caustic potassium of about 50 per cent strength in the manner described in U. S. Patent 1,788,297 into a compound corresponding to the formula NEI The zinc mercaptide of this compound is transformed into the 2.6-dimethyl-5-acetylaminobenzthiazole with a melting point of about 178 C. corresponding to the above formula by heating the aforesaid mercaptide with acetic anhydride. According to the second way 3-chloro-4-acetylprobably the 2.5-diamino-6-methylxylidiri corresponding to the formula aminc-6-nitrotoluene.having a melting point of 143 C. is transformed into 2.6-dimethy1-5-nitrobenzthiazole forming compact, colorless crystals when crystallized from alcohol which melt at about 106 C. This compound yields the 2.6

dimethyl--amino benzthiazole when reduced with iron and acetic acid forming colorless crystals which melt at about 143 C. lThe thiazole can be easily acetylated.

Example 4.--The base 2.4-dimethyl-6-aminobenzthiazole corresponding to the formula HzN S l! 2 I:111%--CH1 is obtained as follows. Acetyl-toluylene-diamine corresponding to the formula.

NHI H is by means of S2012 transformed into the thiazthionium-compound in the manner described' in U. S. Patent 1,637,023. When treating this compound with a solution of caustic alkali according to U. S. Patent 1,243,710k the corresponding oamno-mercaptan corresponding to the formula -CHI is obtainable as follows.' Amino-acetylamino- BIN \CO.CH:

is rhodanated according to U. S. Patent 1,787.315

benzthiazole corresponding to the formula land melting at about 285 C. is obtained. By boiling this compound with va strong aqueous solution of caustic'alkali according to U. S. Patent 1,788,297,1t is split up to the corresponding oaminO-mercaptan, which'may be separated fromv the reaction mixture in form ofthe zinc mercaptide. By heating with acetic anhydride the 2.4.6-trimethyl-7-acetylamino-benzthiazole is obtained. After recrystallization from its alcoholic solution this compound forms colorless crystals melting at about 208 C. By saponilcation with hydrochloric acid the 2.4.6-trimethyl- 7-aminobenzthiazole is obtained in the form of colorless crystals melting at about 128 C.

amino-benzthiazole corresponding to the formula has already been described: cf. Bernthsen, Ann. 251, page 29. r

Example 7 .-The base 2methyl6diethyl vamino-benzthiazole corresponding to the formula from the chloride by means of an aqueous solution o f caustic alkali it separates in the form'of a'yellowoil which solidifies upon cooling.

Eample 8.--The base 2-rnethyl-5-dimethyl- A amino-benzthiazole corresponding to the formula s (CHozN- La 2 N-CH:

is obtainable Vas follows.

phenol by reduction with sodium sulfide in an aqueous alkaline suspension. The latter compound is transformed 4into 2methyl5dimethyl amino-benzthiazole by a treatment with acetic anhydride. The chloride forms colorless crystals which are insoluble in ether, but easily Soluble in water. v

\ 10 cc. of ethyl-ortho-acetate.

pbromo-dimethylanig line is 'nitrated in a mixture of concentrated nitric .5

The formed p-bromo-nitro- Example 9.--The base '2.4-dimethyl-6Fphenylvamino'henzthiazole corresponding to the formulaI Example Ulf-For producing the dye bis-[3- ethyl 5 diethylamino benz thiazole (2) lt-gmethyl-trimethinecyanine; corresponding'to,V e formula 1o grains or 2-methy1-5 diethyiamino-benztmazole-ethyl-iodide of the formula s 1 5g-CH; I/ \CH in cc. of dry pyridine are boiled for l hour with After cooling the dye precipitated from the dark-vlolet-blue solution in pyridine by addition of water. From the solution in alcohol green crystals having the form of needles are obtainable. The dye is easily soluble in alcohol; the blue alcoholic solution shows an absorption maximum at a wave length of about 598W.

Incorporated in a silver-halide emulsion the dye imparts to it range of sensitiveness from about 510W. tol 705ML, with a maximum at about 630M. Example 11.-For producing the dye bis-[3- ethyl-5-diethylamino-benzthiazole- (2) l--ethyltrimethine-cyanine; corresponding to the formula (CsHthN C aHs 10 grams Iof 2methyl-5-dlethylamino-benzthiazole-ethyl-iodide dissolved in `20cc. of pyridine are boiled for about 1 hour with 10 cc. of ethyl v ortho-propionate.' After cooling the dye is precipitated from the blue pyridine solution with the vaid of an aqueous solution of sodium perchlorate of about 5 per cent strength. The dye is then separated by filtration andr washed with water.

Recrystallized from its solution in alcohol the dye Incorporated in a silver-halide emulsion' the dye imparts to ita range of sensitiveness *from about 510ML to about 720ml with about 640ML.

Example 12.--For producing'thedye bis-[3- a maximumat (2) l --methyl-trimethinecyanine; corresponding to the formula 10 grams of 2.6-dimethyl--diethylamino-benzthiazole-ethyl-iodide dissolved in 20 cc. .of pyridine are boiled for about one hour with 10 cc. of ethyl-ortho-acetate, then the dye is precipitated by addition of a small quantity of an aqueous solution of potassium iodide of about 5 per cent strength, the dye is'separated by filtration and washed with water. From its solution in alcohol the dye is obtained in dark green crystals.

The blue solution of the dye in alcohol shows an absorption maximum at a wave length of about 600ML.

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitiveness from about 500 to `'710ML with a maximum at about 580ML which is very flat.

Example 13.-'I'he dye bis-[3-ethyl-6-diethylamino benzthiazole (2)'l--methyl-trimethinecyanine perchlorate corresponding to the formula ortho-acetate While hea-ting for about l hour to 14 0 C. The dye is precipitated from the resulting mixture with the aid of an aqueous solution of sodium perchlorate of about 5 per cent strength.

From its solution in alcohol the dye is obtained in the form of green needles.

The blue solution of the dye in alcohol shows an absprption maximum at a wave length of about 610ML.

Incorporated in a -silver-halide emulsion the `dye imparts to it a range of sensitiveness from about 510ML to about 715ML with a maximum at about 645ML.

Example 14.-For producing the dye bis-[3- methyl--acetylamino benzthiazole-(2) l-methinecyanine; iodide corresponding to the formula l \N6 7 s s 7 6 N Omoo 5 2| I2`I 5 0Comt 4 /owbI/v/ l om I CH3 3 grams of Z-methyl-6-acetylamino-benzthiazolemethyl-iodide are heated with 2.5 cc. of acetic an- Example 15.-For producing the dye [3-ethyl- 6 diethylamino benzthiazole (2) [1 ethyl quinoline- (2) l-methinecyanine; iodide of 2.5 grams of pure potassium hydroxide in about 50 cc. alcohol is gradually added, whereupon the mixture takes immediately a dark red color. After having continued heating for about 10 minutes the mixture is allowed to cool, whereupon the formed dye is precipitated by addition of a small quantity of an aqueous solution of potassium iodide of about 5 per cent strength, separated from the reaction mixture by filtration and recrystallined from alcohol.

The dye is obtained in the form of red-brown thin leaf lamellae. Its solution in alcohol shows a claret color and a dull absorption maximum at a Wave length of about 520ML.

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitiveness from about 480ML to 645ML with a maximum at about 545ML.

Example 16.-For producing the ldye [3-ethyl- 6 diethylamino -1 benzthiazole 7 (.2) l-[l ethyl quinolne (4)] methinecyanine liodide corresponding to the formula a solution of 7.5 Agrams of 5-diethylamino-2- methyl-benzthiazole-ethyl-iodide and 10 grams of quinoline-ethyl-iodide in cc. of alcohol are heated until boiling. To the boilingsolution we add 2.5 grams of potassium hydroxide dissolved in about 50 cc. of anhydrous alcohol, continue with boiling for about 10 minutes the reaction mixture which has become Carmine, add a small quantity of an aqueous solution of potassium iodide of about 5 per cent strength and allow to cool. Then we separate the dye by filtration and recrystallize it from alcohol.

The alcoholic solution of the dye shows a carmine color andan absorption maximum at a wave length of about 545ML.

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitiveness from 500 to 670ML with a maximum at about 570ML.

Example 17.--The dye bi's-[B-ethyl-G-diethyla min o-benzthiazole (2)] trimethinecyanine, iodide corresponding to the formula www 10 cc. of 'Ethyl orthoformate. On addition of a small quantity of a. solution of potassium iodide of about 5 per cent. strength to the cooled reaction Incorporated in a silver halide emulsion the dye imparts to ita range of sensitiveness from about 515ml. to about 730W., with a maximum at about 655ML.

The dye bis-[3-ethyl-5-diethylamino-benzthiazole-(IZ) ]-trimethinecyanine iodide correspond- 'ing to the formula S x l S--l ,7 6

1 i i i 1 (C2H5)2N- YLC=G-G=V 4 5-N(o2n5), (J2/H5 \I v (lJzH is produced in a completely analogous manner by using Z-methyl 5 diethylamino benzthiazoleethyl-iodide instead of 2-methyl-6-diethylaminobenzthiazole-ethyl-iodide. i

The dye shows the same absorption maximum at a wave length of about 625W as the G-bisdiethylamino dye. The range of sensitiveness which the dye imparts to a silver halide emulsion is likewise that o f the 6-bis diethylamino dye, namely 515pa'to 730ML, with a maximum at about 655ML. The spectrogram of this dye is shown in the accompanying drawing. Example 18.--For producing the dye bis-[3.4.6- trimethyl-'7-acetylamino-benzthiazole (2)] trimethinecyanine; bromide corresponding tothe formula v v grams of 2.4.6-trimethyl-7-acetylamino-benzthiazole-dimethylsulfate, 5 cc. ethyl v orthoformate and 10 cc. of dry pyridine are boiled for abou't one hour. After cooling the dye is precipitated by addition of a small quantity of' a solution of potassium bromide of about 5 per cent strength. r

The dye dissolves in alcohol with a red `violet color and the solution shows an absorption maximum at a wave length of about 570ML.

Example 19.-For producing the dye bis-[3- cthyl 6 diethylamino -benzselenazole- (2) l-trimethinecyanine; iodide corresponding to the for- CQHA 5 I 02H5 5 grams of 2-methy1-G-diethylamino-benzselenlazole-ethyl-iodide are dissolved in cc. of hot pyridine and this mixture is boiled for about 1 hour with 5 cc. of ethyl ortho-formate. After cooling thedye is precipitated in the blue pyri- Vdine solution by addition of a small quantity of an aqueous solution of potassium iodide of about 5 per cent. strength. Then the dye is separated from the mixture by ltration and is after recrystallization from alcohol obtained in the form oi. a black blue crystal powder. v

.In the alcoholic solution the dyehas an abrzption maximum at awave length of about Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitiveness from about 510 to 750m with a maximum at about 675W.

Example 20.For producing the dye [3-ethyl- 5 diethylamino benzthiazole-(2)l [3-ethyl-6- ethoxybenzthiazole- (2) l-trimethinecyanine perchlorate corresponding to the formula l we vproceed as follows:

thiazole ethyl-iodide and 6.5 grams of diphenyl- I formamidine are intimately mixed; to this mixture cc. `of acetic anhy ride Aare added and the'whole is vboiled. for 4 hour under reilux (about 140 C.). After c ling thereaction mixture ether is added dro by-drop while stirring the'mixture and rubbing the Walls of the vessel. This procedure is continu d until the formation of crystals occurs at the walls of the vessel. Now, the intermediate product isprecipitated by cool-'- ing the reaction mixture with a freezing mixture and separated by filtration. The intermediate product which melts in its pure state at 218 to 219 C. corresponds probably to the formula tration, 'dissolved in alcohol and precipitated `from its alcoholic solution in the form of its perchlorate by addition of a few cc.` of an aqueous solution of sodium perchlorate of 1 per cent.

strength and water.

After recrystallizationgo-f the dye, its alcoholic solution shows an absorption [maximum at a wave length of about 600ML.' v

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitiveness from about 500ML to about 715ML with a maximum at about 625ML.

- Example 21,-For producingthedye [B-ethyl- 5 diethylamlno benzthiazole (2)l [3 ethylbenzthi azole- (2) l-trimethinecyanine Aperchlorate corresponding to the formula 4 grams of the intermediate product obtainable from 5 diethylamino 2 methylbenzthiazoleethyl-iodide and diphenyl-formamidine in the manner described in Example 20 sub A, are boiled (C2-HANN- with 2 gramsv of 2-methyl-benzthiazole-ethyliodide and 20 cc. of pyridine for hour under reux (125 to 130 C.). The reaction mixture is Worked up in the manner indicated in Example 20.

'Ihe dye shows in its alcoholic solution an absorption maximum at aA wave length of about 595ML. 1

Incorporated in a silver-halide emulsion the dye imparts to it a range of sensitiveness from about 510ml to about 720ML with a'maximum at about 6351141.,

Example 22.--The dye [3 ethyl 6 diethylaminobenzthiazole- (2) l#lBLethyI-benzselenazole- (2) -methinecyanine iodide corresponding to the formula may be produced by mixing 1.5 grams of the intermediate product described in Example 20 with 2.3 grams of 6-diethylamno-2-methylbenzothiazole-ethyl-iodide and 15 cc. of pyridine, boiling this mixture for 3/1; hour under reflux and Working up the reaction mixture asl indicated in Example 20. The dye may likewise be obtained as 1 iodide or bromide.

The'alcoholic solution of the dye has an absorption-maximum at a wave length of about 625ML.

A silver-halide emulsion containing the dye is sensitized to the waves from about 510W. to about 730ML, with a maximum at about 655ML.

Example 24.-For producing [B-ethyl--diethylamino-benzthiazole-(2)l [1 ethyl-quino (2)]-trimethinecyanine iodide corresponding to the formula 5 grams of the intermediate 'product obtainable from 5-diethylamino-2 methylbenzthia'zole ethyl-iodide and diphenyl-formamidine as described in Example 20, are boiled for 21/2 hours with 4 grams of quinaldine-ethyl-iodide and 15 cc. ol. pyridine under reflux. The' dye which forms is precipitated by addition of a few cc. of an aqueous solution of potassium iodide of per cent. strength and Water and is recrystallized from alcohol.

'I'he alcoholic solution of the dye has an absorption maximum at'a wave length of about 615ML.

'Incorporated in a silver halide emulsion the .dye imparts toit a range of sensitiveness to 2 grams of the intermediate product obtainablel from 5 diethyl 2 methylbenzthiazole-ethyliodide and diphenyl-formamidine are boiled for 11/2 hours with 1.5 grams of trimethylindolmethyl-iodide and 10 cc. of. pyridine under reflux. To this mixture while still Warm there are added a few cc. of an aqueous'solutlon of potassium iodide and water. While cooling the reaction mixture the dye separates in the form of its iodide. Eventually as by-product formed symmetrical carbocyanine from trimethyl-indolethyl-iodide may be removed by fractional crystallization.

In its alcoholic solution the dye shows an absorption maximum at a wave length of about 585ML. 1

Incorporated in a` silver-halide emulsion the dye imparts to it a range of sensitiveness from about 510ML to about 700W. with a maximum all abOllt 620ML.

- Further dyes which may be prepared according to the methods described in the foregoing examples are:

(1) [3-ethyl-6-diethylamino-(2)l [3 ethylbenzthiazole- (2) l-trimethin'ecyanine perchlorate corresponding tothe formula Absorption maximum of the alcoholic solution: about 600ML.v

An emulsion containing the dye is sensitized to Waves from about 500ML to about 720ML, with a maximum at about 630ML.

inecyanine-iodide corresponding to the formula y Absorption. maximum of the alcoholic solution: about 600ML. An emulsion containing the dye is sensitized to waves from about 520ML to about 710ML, With a maximum at about 630M/r.

accesso I methinecyanine perchlorate corresponding'to the formula l H H El; y o 00ml sai-Ni O/Hl 0104 am v Cl'l \I Absorption maximum ofV the alcoholic' solution: about 525ml..

An emulsion containing the dye is sensltized to waves from about 500ML to about 650W with a maximum at about 570W.

(5) [3 ethyl 6 acetylamino benzthiazole- (2) l-[l-ethyl-B-methyl-quinoline (2) meth inecyanine iodide corresponding to the formula An emulsion containing the dye is sensitized to waves from about 480p/l to about605pa with a maximumat about 550ML.

(7) [3-ethyl-6-propionylamino benzthiazole (2) l-II-ethyl--methyl-quinoline- (2) l meth inecyanine iodidecorresponding to the formula CBu . cs Bl An emulsion containing the dye is sensitized to waves from yabout 500ML to about 600MLA with' amaximum at about S40/m. v 4

I t isto be understood that our invention is not limited' to the foregoing examples nor to the specltlc details given therein. Numerous other embodiments are possible 'and we contemplate as included within our invention all such modincations and equivalents as fall within the scope 75 ci the appended claims. `'.i'hus y' in the general formula may also represent oxygen. Weobtain v then benzthio-oxo-cyanines or benzthio-'oxocarbocyanines. In the same manner Y in the general formula may represent C (CHs): and oxygen.

The formulae ofthe dyes given herein represent the molecular structure ci our new dyes so far as to our actual knowledge. It, however. in future it should become evident that the formulae dciN not exactly correspond to the dyes this fact will n'ot aiect our invention since the dyes will be easily .identified by the method of producing the same which has been fully described in the examples. The maxima of sensitiveness of our dyes are all very dat and the values indicated mayk `not vbe regarded too critical.

The selenocarbocyanines substituted 'in the central atom (pz-position) of the carbon bridge form the subject matter oi the copendlng applications Ser. No. 617.468, flledJune 17, 1932, by

Wilhelm Schneider and Ser. No; 591,389, led Feb. 6, 1932. by Walter Zeh, and are vnot claimed in this application.

In the-appended claims the expression an amino group" is to be erstood as including not only the amino gr but also substituted amino groups.

,What we claim is:

1. .A photographic ma \rial which comprises a lsilver halide emulsion containing a trimethinecyaninedye selected from the group consisting of benzthiazo'le trimethinecyanine salts and benzselenazole trimethinecyanine salts symmetrically substituted in the benzene nuclei by a radical selected from the group consisting of amino groups', dialkylamino groups. and acylamino groups.

2. A photographic material which comprises a silver` halide emulsion containing a trimethin'ecyanine dye selected from the group consisting of benzthiazole trimethlnecyanine salts and benzselenazole trimethinecyanin'e salts symmetrically substituted in the benzene nuclei by a lradical selected from the group consisting of amino groups, dialkylamino groupsand' acyl-'- amino groups, `and a radical selected from the groupV consisting of alkyl 'and alkoxy.

3. A photographic material which comprises a silver halide emulsion containing a trimethinecyanine dye selected from the group consisting of benzthiazole trlmethinecyanine salts and benrselenazole trimethinecyanlne salts symmetrically substituted in the benzene nuclei by an amino group.

4. A photographic material which comprises a silver halide emulsion containinga trimethinecyanine dye selected from the group consisting of benzthiazole trimethinecyanine salts and benzselenazole trimethinecyanine salts symmetrically substituted in the benzene nuclei by an amino group and having linked to the central carbon atom of the trimethenyl chain an.` alkyl group. i

5. A photographic material which comprises a silver halide emulsion containing a trimethlnecyanine dye selected from the group consisting 'of benzthiazole trimethinecyanine saltsvand benzselenazole trimethinecyanine salts symmetrically substituted in the benzene nuclei by an amino group and having linked to the central carbonl l,

CaHn I IBI 8. A photographic material which comprises a silver halide emulsion containing bis-[S-ethyl-- diethylamino-benzthiazole-(Z) l trlmethinecyanine iodide corresponding With the formula 02H5 CzHs 9. A photographic material which comprises a silver halide emulsion containing bis-[3-ethyl-6- diethylamino benzselenazole (2)] trimethlnecyanine iodide corresponding with. the formula WALTER DIETERLE. WALTER zEH. WERNER ZERWECK.

7 o NiHi), 

